Sand screen sand saver

ABSTRACT

This is a special downhole sand screen assembly for oil and other fluids containing sand. This invention is called a sand screen sand saver and was developed especially for use with multi-layer concentric sand screens in which the outer screen has larger openings to retain the coarser sand particles and the openings in the inner screen are progressively smaller to retain the less coarse sand particles. The sand screen sand saver causes the sand to be retained so that it can form a sand pack between the outer screen and the well casing.

United States Patent 11 1 1111 3,766,981

Rundt Oct. 23, 1973 [5 SAND SCREEN SAND SAVER 3,313,352 4/1967 Tennison et a1. 166/202 3,316,971 5/1967 Brown 166/202 x [75] lnvemor- Rum, Tulsa Okla- 3,381,755 5/1968 Morrison 166 202 x 73 Assignee: Amoco Production Company, Tulsa 3,637,010 l/l972 Maly et al 166/51 Okla.

Primary Examiner-David H. Brown [22] Filed: 1972 Att0rneyPaul F. Hawley et a1. [21] Appl. No.: 280,691

- [57] ABSTRACT v [52] US. Cl. 166/202, 166/224 This is a Special downhole Sand Screen assembly for oil v[51] [1.1L Cl E211) 33/126 and other fluids containing sand This invention is [58] Field Of Search ..l66/202-205, 224,

called a sand screen sand saver and was developed especially for use with multi-layer concentric sand screens in which the outer screen has larger openings [56] References Cited to retain the coarser sand particles and the openings in UNITED STATES PATENTS the inner screen are progressively smaller to retain the 2,282,987 5 1942 Bennett 166 202 x less r e and particles. The sand screen sand saver 2,602,514 7/1952 Althouse.. 2,887,347 5/1959 Losey 2,935,132 5/1960 Arterburg et al..

..... 166/202 causes the sand to be retained so that it can form a l66/202 X sand pack between the outer screen and the well cas- 3,l19,45l 1/1964 Hall 166/202 3,153,451 10/1964 Chancellor et a1. 166/202 X 5 Claims, 4 Drawing Figures PAIENIEI] on! 23 an FlG.2

SAND SCREEN SAND'SAVER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a sand filter forproducing fluids through wellbores from subsurface formationsult relates especially to amuIti-layer sand screen with special means to retain produced sand between the sand screen and the casing.

2. Setting of the Invention Oil and gas are produced from underground .formations through wellbores drilled from the surface to the formation. Someoil and gas is contained in the pores of consolidated rocks or sand. When this oil is produced through the wellbore, it is relatively free of any rock particles or sand. However, many oil and gas wells produce fluid from underground formations which are not consolidated. That is, the various sand particles are not strongly attached to each other and when the fluid is produced, it carries entrained sand with it which causes serious damage to well equipment. In producing oil and gas from such unconsolidated formations, some method must be provided to restrain the sand inflow into the well. There are numerous methods which have been used to combat this problem. They include (a) placing a screen in the well with sufficiently small openings to prevent inflow of all undesired materials; (b) use of a gravel pack placed in the annular area between the screen and the formations; the voids between the gravel grains being small enough to prevent inflow of sand; and (c) placing a screen in a well consisting of a mechanical screen and a pre-formed gravel pack attached to the screen.

One of the most promising methods of controlling sand in producing wells is the system using a multi-layer well screen described in U.S. Pat. application Ser. No. 77,492, now U.S. Pat No. 3,712,373, filed Oct. 2, 1970, William G. Bearden, et al.

The following U.S. Pats. relate to mechanical means of combating the sand production problem and although not at all exhaustive give a fair representation of the art in this'area of which I am aware:

2,776,001 Clark v 3,216,505 Johansson 3,262,499 Fleming 3,316,971 Brown 3, 81,755 Morrison Some of these Patents show a packer set on a mandrel beneath a slotted liner to retain gravel so that a gravel pack may be formed in' the wellbore at a specific location.

BRIEF DESCRIPTION OF THE INVENTION A cup or other basket-like sand-retaining means is affixed to the lower end of a sand screen for use in a wellbore to obstruct the annular space, between the sand screen filter at its lower end and the casing. As

fluid containing sand is produced through the filter, the more coarse particles are blocked by the sand screen, the cup or sand screen saver (SSSS) will prevent the coarse particles from falling from the sand screen casing annulus to a void below the screen. The formation of this sand pack greatly increases the effectiveness of any sand control system using sand screens and also avoids the difficulties and expense of running gravel packs.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE INVENTION Attention is first directed to FIG. 1 which illustrates a borehole 10 drilled through a producing formation having upper zone 12 and a lower zone 14. These formations will be assumed to produce a fluid such as oil which contains sand entrained therein in sufficient quantities to cause sand production problems. A casting 16 is mounted in hole 10 and cement l8 fills a portion of the void between the casing and the borehole wall. Casing 16 has perforations 38 and 39 adjacent zones 12 and 14.

I show an upper sand control device 20 and a lower system 22. These are connected into a tubing string 24 suspended in casing 16 and it is through this tubing that production is transported to the surface. For the purpose of this illustration, it will be assumed that zones 12 and 14 are part of the same underground reservoir or in any event can be produced through the same tubing string. It is important that screen assembly 20 and 22 be reasonably well centered in casing 16. I obtain this by use of upper centralizer 26 above screen 20, central izer 28 below screen 22 and centralizer 30 which is immediately below 34. Upper sand screen assembly 20 and lower assembly 22 are essentially identical. Thus, the discussion will center mainly on only one of these, namely, the upper assembly. Upper sand assembly 20 includes a sand screen filter 32 which for best results is a multi-layer sand screen filter as described in U.S. application Ser. No. 77,492, supra. I have added a sand screen sand saver 34 to sand screen 32. Various configurations of sand screen sand saver 34 are shown in FIGS. 2, 3 and 4, and will be described later. In order for sand screen 32 to operate at maximum efficiency, the annulus 36 between screen 32 and casing 16 should become filled with entrapped sand as the well is produced and the formation sand entrained in the fluid screens out on the outer layer of the sand screen. If the annulus space 36 is sufficiently small, a formation sand "as production is maintained. However, it has been found that if either the annulus is too large or if production is stopped, the entrapped sand which forms a bridge frequently drops out to the annular void 36A between casing 16 and tubing 24B below the sand screen 34. I eliminate these problems by the use of my sand screen sand saver 34 which is secured to tubing exten- .sion 24A above the tubing collar 59 which extends beneath the sand screen 32. The portion of the tubular member within sand screen 32 between the main tubing string and tubing extension 24A is ordinarily a section of slotted or perforated pipe (not shown in the drawing) connected directly into the tubing string 24.

Fluid is produced from zone 12 through perforations 38 through the openings in the sand screen 32 and eventually through the slotted pipe and up the tubing. The lower end of the tubing is closed. The outer layer of screen 32 has perforations which are sufficiently small so as to stop the larger sand particles being produced with the fluid through perforations 38. These sand particles drop out into annulus 36.'Any tendency for the sand particles to fall to below screen 32 is prevented by my sand screen sand saver 34 and assures the retention of a sand pack between the screen and the casing. I can thus have reasonably large clearance between sand screen 32 and casing 16, for example, from about 1.25 inches to as large as convenient. Further, if I should have to stop production to make repairs at the surface for some reason, then with my invention there is no danger of the sand, which has formed a very efficient filter in annulus 36, falling out, which might occur if my sand screen sand saver were not used. Thus, when l resume production, my sand system filter 20 is operating at maximum efficiency. There is no low efficiency period.

Attention is directed to FIG. 2 for a simple form of my sand screen sand saver. Shown there is a cup 40 having a lower portion 42 which has an internal diameter D, which is essentially the same as the external diameter of tubing extension 24A. It has an intermediate section which tapers upwardly and has an upper section 44 which has an outside diameter D, which is essentially the same as the inside diameter of casing 16.-This hollow member may be clamped or otherwise secured to tubing extension 24 immediately below sand screen 32. This sand screen sand saver can be made of molded rubber or it can be made of metal.

Attention is now directed to FIG. 3 which illustrates some preferred features of my sand screen sand saver. This one embodiment is shown having a plurality of ports sloping inwardly and downwardly through section 40. A flexible slotted annular member 48 inside section 40 is secured at its upper edge 50 to section 40. This serves as a check or flapper valve for ease in running the device in fluid-filled wells to reduce pressure surges against the perforated or exposed formation. However, once the device is in position, sand will be retained on top of annular valve 48.

From time to time, most wells are subject to workover problems in which case the tubing 24 must be pulled from the well. This also will pull the sand screen. If my sand screen sand saver 34 is made of metal of too high strength, then it would become nearly impossible to pull the tubing string. I relieve this problem by several methods. I can simply make the material sufficiently strong to retain sand for the length of the sand screen but sufficiently weak so that I start to pull it, it will collapse. Preferably, I can aid this by forming a circumferential groove 52 in section 40 to weaken thesand saver.

As shown in FIG. 3, L, is the vertical component and L, is the horizontal component of the dimensions of section 40. It is a fact that sometimes centralizers '26 and 30 have sufficient clearance so that tubing 24 is not completely centered. Even though sand screen 32 is not absolutely centered, my invention will still function. One precaution I can take to help insure this is to make L,/L 2 2. This gives me flexibility so that if D, is approximately the same as that of the inside of the casing, then the upper section 44 will contact the inside of casing 16 and form a sand-retaining seal therewith.

Attention is now directed toFIG. 4 for another embodiment of my sand screen sand saver. I show there a base collar 54 with screws 56 so that collar 54 can be firmly attached to tubing extension 24A immediately below sand screen 32. I make my cup portion from a plurality of upwardly extending flexible petal-like elements 58 which can be made from sheet steel. The spring-like elements 58 expand or fall outwardly againstthe inside of the casing and form an upwardly facing bucket to catch the sand. When it is required to pull the sand screen 32, these resilient petal elements will be easily inverted so that the entrapped sand can fall down and not stick the sand screen in the casing.

I have shown two spaced-apart sand screen assemblies 20 and 22. However, my invention works equally well for one assembly or for any reasonable number.

While the above invention has been described in detail, it is to be understood that various modifications can be made thereto without departing from the spirit or scope of the invention.

I claim:

1. A sand screen sand saver for use with a sand screen supported by a tubing string suspended in a casing lining a wellbore which has perforations opposite an underground producing formation which comprises a hollow cup-like member having a lower cylindrical portion,

an upper cylindrical portion of larger diameter than said lower portion,

an intermediate truncated cone portion connecting said lower section and said upper section, said intermediate section having a plurality of ports therethrough sloping inwardly and downwardly.

2. An apparatus as defined in claim 1 including check valve means closing said ports.

3. An apparatus as defined in claim 2 in which Is /L 2 where L is the longitudinal distance between said lower section and said upper section and L is the difference between the radius of said lower portion and the radius of said upper portion.

4. An apparatus as defined in claim 3 including a circumferential groove in the lower exterior portion of said intermediate section.

5. A sand screen saver for use with a sand screen supported by a tubing string suspended in a casing lining a wellbore which has perforations opposite an underground producing formation which comprises a hollow cup-like member having a lower cylindrical portion,

an upper cylindrical portion of larger diameter than said lower portion, an intermediate truncated conical portion connecting said lower section and said upper section, said intermediate section including a circumferential groove in the lower part .of said intermediate section.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 766,981 Dated October 23, 1973 Inventor(s) Ronald Rundt It is eertified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

(2o1umn 1, line 44, "2,776,001 Clark" should read --2, 776,011 Clark-;

' line 48, "3, 81,755 Morrison" should read --3,381,755 Morrison--; line 61, "sand screen saver (8888)" should read --sand screen sand saver (SSSS)--.

Column 3, line 38, "ports sloping" should read -ports 46 sloping--; line 54, "that I start to pull" should read --that when I start to pull--.

Column v4, line 41, "claim 2" should read -claim 1--.

Signed and sealed this 6th day of August 1974.

(SEAL) Attest:

McCOY M. GIBSON, JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. A sand screen sand saver for use with a sand screen supported by a tubing string suspended in a casing lining a wellbore which has perforations opposite an underground producing formation which comprises a hollow cup-like member having a lower cylindrical portion, an upper cylindrical portion of larger diameter than said lower portion, an intermediate truncated cone portion connecting said lower section and said upper section, said intermediate section having a plurality of ports therethrough sloping inwardly and downwardly.
 2. An apparatus as defined in claim 1 including check valve means closing said ports.
 3. An apparatus as defined in claim 2 in which L1/L2 > or = 2 where L2 is the longitudinal distance between said lower section and said upper section and L2 is the difference between the radius of said lower portion and the radius of said upper portion.
 4. An apparatus as defined in claim 3 including a circumferential groove in the lower exterior portion of said intermediate section.
 5. A sand screen saver for use with a sand screen supported by a tubing string suspended in a casing lining a wellbore which has perforations opposite an underground producing formation which comprises a hollow cup-like member having a lower cylindrical portion, an upper cylindrical portion of larger diameter than said lower portion, an intermediate truncated conical portion connecting said lower section and said upper section, said intermediate section including a circumferential groove in the lower part of said intermediate section. 